Increasing populations continue to produce a growing amount of waste material. Landfills are near capacity in some sites and there are those people that feel that landfills are a temporary solution with problems that surface in the future. Eliminating waste through some conventional means can produce other sources of contamination or waste that must be dealt with separately. In addition to managing waste disposal, some conventional waste processing techniques utilize heavy, fossil fuel run machinery whose fuel consumption collaterally produces further environmental contamination. Thus, while such equipment attends to one problem, their efficiency in eliminating or processing waste material can lead to undesirable results.
In The United States, some laws restrict the processes utilized to convert waste material. Simple torching and burning of indiscriminately mixed materials can produce thick plumes of noxious smoke and the mixed materials burned together can produce unintended combinations of poisonous gases or other chemical residues deleterious to the environment. Some efforts controlled processing by employing the use of ovens. In breaking material down, some of the material constituents reform as a gassed off vapor that may include volatile organic compounds (VOCs). VOCs that escape into the atmosphere readily react and contribute a negative impact on the environment. Thus, some efforts have led to implementing recycling techniques that are friendly to the environment by reducing the deleterious by-products from waste conversion and equipment operation.
One solution is to exploit the benefits of pyrolysis by processing material in an oxygen depleted environment. Ovens employing a pyrolytic environment will operate at temperatures typically above 800° F. where the heat and pressure cooperate to break down the chemical bonds of waste material. In an oxygen depleted environment, less gassing off occurs and less volatile organic compounds and smoke are produced than in conventional incineration techniques. A majority of the material is converted to char while other by-products may include oils. One of the benefits of pyrolytic processing derives from these byproducts being energy rich and reusable as a fuel source in other applications or for the oven itself. Thus, efficiency in extracting the energy rich constituents of waste materials is conducive to achieving optimal recycling of waste material.
The skilled artisan recognizes that inefficiency can lead to redundancy in processing material and thus, negatively impact the goal of producing an environmentally friendly converted product. Under-processed waste material can suffer twofold. In one sense, under-converted material translates into a loss of fuel product as the energy rich constituents of the waste material remain in their unusable state. In another aspect, under-converted material drives up operation costs as material must be re-introduced into the oven impacting both machinery fuel usage and material conversion production rates.
Some early retort ovens used a static approach to processing. Incinerators included a removable, heat resilient platform where material was placed onto the platform and inserted into the oven. After sufficient charring of material, the platform was removed and the ashes loaded into vessels for transport and additional waste material was loaded onto the platform and reinserted. Ovens using this kind of approach suffered from a slow processing rate of waste material.
Other solutions employed a conveyor system to move waste through an oven chamber converting the material into gas and Char and mechanically moving it out of the oven. Ovens of this type sometime suffer from periodic breakdown after multiple moving parts wear down in a superheated environment. Additionally, the construction of some ovens of this type exposed the oven chamber to external air allowing undesirable gases to escape uncontrolled into the environment.
Another proposed solution can be seen in U.S. Pat. No. 7,032,525 to Edmondson that teaches an oven using an angled ramp fixed in place between a material entrance and material exit where the oven interior is heated by a flue gas. The material to be processed is intended to glide or fall along the ramp from the material entrance to the material exit. An oven of this type suffers from an inability to adjust the movement rate and retention time of waste materials being processed so as to obtain an optimal charring result.
It can be seen therefore that a need exists in the art for a retort oven in which the waste material flow path may be adjusted in deck-angle fashion, thereby allowing for various types of waste materials to be retained within the oven for different times while providing an efficient, material transfer system.